Abstract: Reactor pressure vessel (RPV) operating under intense neutron irradiation for a long time will suffer radiation damage, which will affect its service life. Aiming at this problem, based on the principle of magnetic Barkhausen noise (MBN) effect, a three-dimensional simulation model of Barkhausen sensor is established. The validity of sensor structure and its optimal parameters are verified by simulation results. At the same time, a portable detection system for irradiation embrittlement of small size RPV steel is developed, which is based on the development board of TMS320F28335. Then, the repeatability and stability of the system are further verified.